A new report warns that Internet service providers are facing an unrelenting barrage of distributed denial of service attacks aimed at crashing the network.

Arbor Networks said Wednesday that its survey of Tier 1 ISPs and Tier 2 network operators found that the DDoS remains the most worrisome Internet security threat, and that their number and scale are steadily increasing.

Despite the concern, only 29 percent of the companies surveyed said they offer security and other service agreements related to DDoS to their commercial clients.

"The report clearly indicates that an entire criminal economy is evolving around denial of service activity and is driving some service providers to offer new network-based security services to combat these attacks," said Arbor's Dan McPherson.

The DDoS attacks most often involve the compromising of hosts through the use of so-called zombie networks and "botnets" that can grow in size up to a gigabit.

Copyright 2005 by United Press International